Pot-type oil burner and ignition system therefor



Sept. 14, 1954 R. F, VAN TUBERGEN 2,688,999

POT-TYPE OIL BURNER AND IGNITION SYSTEM THEREFOR Filed Nov. 29, 1949 2Sheets-Sheet l 24 IJ'IVQTJ'OI" Ill Ti Richard FVEm Tube qen Sept. 14,1954 R. F. VAN TUBERGEN POT-TYPE OIL. BURNER AND IGNITION SYSTEMTHEREFOR Filed Nov. 29, 1949 2 Sheets-Sheet 2 IIYI Rz'c hcf'd Evan Tubegen Patented Sept. 14, 1954 BOT-TYPE OIL BURNER AND IGNITION SYSTEMTHEREFOR Richard F. Van Tubergen, Portland, Oreg. Application November29, 1949, Serial No. 129,941

1 Th present invention relates to an ignition system for controllingautomatically the operation of burners consuming oil and other liquidfuels.

In the conventional oil burner, a problem is presented by the tendencyof the burner to snuff out because of drafts occurring within thecombustion chamber. This problem is particularly acute during theinitial period of operation immediately following the lighting of theburner and before the burner and combustion chamber have becomethoroughly heated.

Currently manufactured oil burners are provided with a float-operatedvalve in the conduit conveying fuel to the burner. This is disposed withreference to the floor of the combustion chamber in such a manner that,if the burner is snuffed out, the oil which subsequently accumulateswill back up into the float chamber, raising the float, operating thevalve, and shutting off the flow of oil. This does not occur, however,until well over an inch of oil has accumulated in the combustionchamber. If the accumulated oil is not removed before relighting theburner, a dangerous conflagration may occur. Also, with the abovedescribed mechanism, it is possible to re-ignite a snuffed out burner inthe presence of an accumulation of oil while the burner is still hotenough to vaporize some of it with the result that an explosion mayoccur.

It is a primary object of my invention to provide an igniter for oilburners which will automatically reignite a burner which has beensnuffed out thereby preventing the accumulation of oil in the combustionchamber with attendant difliculty of lighting the burner.

It is another important object of my invention to provide an automaticigniter for oil burners which will operate effectively during the periodimmediately following the initial ignition of the burner, reigniting itimmediately if it should become snuffed out.

It is a further object of my invention to provide an automatic igniterfor oil burners which may be located out of the combustion zone, therebymaterially improving its operation and prolonging its service life.

Still a further important object of my invention is the provision of anautomatic igniter for oil burners which is electrically operated butwhich is provided with means for preventing the ignition of accumulatedoil in the event of a power failure.

It is another object of my invention to provide an automatic igniter foroil burners which is Claims. (01. 15828) versatile and may be applied toburners of the various current constructions as well as in theconstruction of new types of burners.

It is still a further object of my invention to provide an automaticigniter for oil burners which may be placed in operationcontemporaneously with the turning on of the fuel supply througactuation of a single control.

It is still a further object of my invention to provide an igniter foroil burners which is of simple construction and inexpensive to make.

"The manner in which the foregoing and other objects of the presentinvention are accomplished will be apparent from the followingspecification and claims considered together with the accompanyingdrawings wherein:

Figure 1 is a View in elevation, partly in section, of the automaticigniter of my invention applied to the inlet assembly of an oil burnerof the class which may be used in the heating of domestic and industrialbuildings;

Figure 2 is a schematic view in elevation of the inlet assembly ofFigure 1;

Figure 3 is a wiring diagram of the igniter illustrated in Figure 1;

Figures 4 and 5 are detail views of a wick which may be employed in theoperation of the igniter illustrated in Figure 1;

Figure 6 is a fragmentary View in elevation partly in sectionillustrating an alternate construction of an igniter control for usewith the igniter of my invention;

Figure '7 is a fragmentary view partly in section illustrating stillanother embodiment of an igniter control for use with the igniter of myinvention;

Figure 8 is a fragmentary view partly in section of still another typeof an igniter control for use with an igniter embodying the concept ofmy invention;

Figure 9 is a fragmentary view partly in section of yet another ignitercontrol ignition system embodying my invention; and

Figure 10 is a fragmentary view partly in section illustrating still afurther means for operating the igniter of my invention.

Generally stated, the automatic igniter for oil burners disclosed hereincomprises an electric resistance element such as a Nichrome wire placedadjacent the burner and adapted to ignite the same. A switch is placedin an electric circuit with the resistance element and temperatureresponsive means such as a bimetal blade are placed adjacent thefurnace. The bimetal blade actuates the switch, turning it on when thetemperature 3 drops below a predetermined level, thereby igniting theburner, and turning it off when the temperature reaches or exceeds thepredetermined level. This turns off the igniter until such time as thebimetal blade cools sufliciently to.

close the switch, again establishing the electric circuit through theresistance element. Switch means also may be provided for making andbreaking the circuit including the resistance element contemporaneouslywith the turning on and off of the fuel supply to the burner. Means alsomay be provided for turning off the igniter in the event of a powerfailure.

Referring now to Figures 1 to 5;

The automatic igniter of my invention is illustrated applied to aconventional'oil burner comprising the casing Ill having at the bottomthereof an opening II for the introduction of air to the interior. whichcontains an upper burner ring [3 and a lower burner ring It; and whichhas an arcuate' A conventional burner 46 is placed adjacent thebottom'of the burner pot. It is supplied with oil through the conduitchamber 18. sembly of conventional construction (Figure 2) including avalve [9 for turning onand off the flow of oil through the conduit 11, arotatable control shaft 20 for operating the valve, and a float chambercontaining a float 21. These elementsare-arranged in such a manner thatwhen oil is admitted to the chamber through conduit 22 by opening valve24, it accumulates in the chamber until'it has reached a levelat whichit may overflow into conduit upon opening of valve I9, whichconveys itto the burner.

The float 2| is attached to a-pivotally mounted arm 23' and is placed ata predetermined elevation above the floor l5 of the burner pot. Upon theaccumulation of oil in the latter inthe event of a snuff out of theburner, the level of the oil in the float chamber rises to the levelindicated 1 by the dotted line in Figure2 which isthe flood level of theburner pot, thus liftingthe float 2i.

The upward motion of-the floatis used to actuate valve 24 and shut offtheflow of oil, preventing. further flooding of the-burner pot. in Wellknown manner. It also is usedto actuate an extension 23a of arm 23,which extends outwardly from chamber l8 for a purpose to bedeveloped-hereinafter.

Fuel introducedto the burner: it through the line I! isignitedwithin thecombustion. chamberv bymeans of suitable ignition means such. as theelectric resistance element 25 which:

bottom of the burner pot to'the vicinity of the resistance element. Thispreferably is made from reinforced'woven asbestos (brake lining) orother porous, noncombustible material. tained in position by means ofthe holder 27! on which is a knuckle 28 through which extends theresistance element 25. In this manner the wick is supported by andbrought into close proximity to the resistance element.

Within the casing is a burner pot i2 l! emanating from the The lattercontains an inlet as- It is main-- energized and (lo-energizedcontemporaneously The Nichrome or other resistance element isincorporated in a suitable electric circuit via electric conductor 30passing through a plug 3| which is threaded into the casing and extendsinto the burner pot through aligned openings in the sides thereof. Theelectric circuit includes a transformer 32 for supplying current atproper voltage to the resistance element 25, anda first electric switch33' which may be. a mercury switch or a microswitch. The latter isoperated by means of the cam follower 34 associated with cam 35 on theshaft 20 by means of which'the flow of oil to the burner is controlled.It will be apparent that when the shaft 20 is rotated to start the flowof oil into the burner the cam'35 will assume the position indicated indotted outlinein Figure 3, thereby moving the cam follower and closingthe switch 33. The motion of the cam follower, however, is against thetension of a spring 36, which will return it to its original positionwhen shaft Ml-is turned to shut off the flow of oil. This breakstheelectric circuit, In

this manner, the resistance element 25 may be with the turning on andshutting off of the-flow of oil to the burner;

A second switch 40, preferably a mercury switch, is in series in thecircuit with the first switch and the resistance element. It. has-foritsfunction the breakingof the.- circuit and'conse quent ole-energizing ofthe resistance element after the burner is in full operation; To thisend it is associated with combustion responsive means stationed in thefurnacearea, preferably-adjacent the burner pot and designed to respondvto the temperature changes thereof; in such a manner as to open theswitch 40 when the:temperaturein. such a manner as to extendapproximately to the center of the opening II and in close. prox-- imityto the base l5 of the burnerpot. The spacing of the blade or other, heatresponsive element from the burner pot is variable, however, beingdetermined in part by the operating temperature of the burner. Where theburner operates at alow temperature, reaching a maximum temperature ofabout 500 F., the bimetal blade-may be placed closely adjacentthebottom'of the burner pot. However, where the burner operates athigher temperatures, the distancebetween the bimetal blade and theburner pot may be increased.

It will be apparent that both the burner temperature and the spaceseparating the bimetal blade from the bottom of the burner potwilldetermine the time interval ensuing between lighting of the burnerand actuation of the bimetal blade. This, in turn, will determine thelength of the period during which the electric resistance member remainsenergized. In general, the space separating the bimetal blade and theburner pot should be such as to maintain theresistance element energizedthrough the complete vaporization stage of the burner until the latteris in full operation, which usually requires about seven minutes. Thisinsures reignition of the burner if it should be snufiedout duringthecritical initial period.

This is bolted or otherwise.

Similarly, the space between the bimetal blade and the burner pot shouldbe such as to cause closing of switch 40 and ignition of the burnerprior to the accumulation of a large amount of oil upon snufling out ofthe burner after it is in full operation. I have found, however, thatthe unburned oil entering the burner pot cools the floor of the samerapidly, so that the desired rapid closing of the switch 40 will beachieved. In general the time required to close this switch upon coolingof the burner pot will approximately equal that required to open it uponheating of the burner pot during the initial operating stage.

Actuation of the switch 40, and hence of the electric resistance elementis accomplished in the embodiment of Figures 1 to 3 by attaching amercury switch directly to the bimetal blade and positioning it thereonin such a manner that the switch will be closed when the blade is in itsnormal position adjacent the burner pot, but open when the blade isdisplaced by the increasing temperature of the burner pot until itassumes the position shown in dotted outline in Figure 3.

Means also are provided for maintaining the resistance element 25de-energized when the electric service is resumed after a power failure.This is important, since, if the burner is snuffed out during such powerfailure, the closing of the switch 40 upon cooling of the bimetal bladecannot energize the resistance element and reignite the burner. As aresult, oil will continue to flow through the conduit I! and willaccumulate in the bottom of the burner pot. Then if the resistanceelement 25 Were to become energized upon resumption of the power supply,the ignition of a large quantity of oil would occur.

There is provided, therefore, within the chamber l8 level responsivemeans such as float 2| operating in conjunction with the valve 24 forturning off the flow of oil when the float reaches a predetermined leveldetermined by the depth of the oil in the bottom of the burner pot. Asstated above, the chamber I8 is arranged so that the float 2| isactuated when somewhat over an inch of oil has accumulated in the burnerpot. This shuts off the valve 24. At the same time it elevates the arm23a to the position shown in dotted outline in Figure 3. This opensswitch 45 which, like the previously described switches 33 and 40, is inseries circuit relationship with the resistance element. Switch 45 willremain open as long as the float 2| remains elevated by the floodingoil. Therefore, when the electric service is resumed, the resistanceelement 25 will not become energized even though switch 40 has beenclosed by the cooling of the system and the consequent return of thebimetal blade to its normal position adjacent the bottom of the burner:pot.

For convenience, several of the foregoing elements comprising theignition device of my inures 6 to 10, inclusive. Thus, as is shown inFigure 6, a spiral 50 of a heat sensitive metal wound on a suitable coreand supported on a suitable base 5| may be inserted through an openingin the base of the casing. Upon being heated, the metal comprising thespiral will expand, the resulting motion being used to open a switch 52,corresponding to switch 40 of Figure 3. This will break the circuit andshut off the resistance elevention may be incorporated in a single unit.

Thus the switches 33 and. 45, the transformer 32, and the cam fol-lower34 with attached spring 36 may conveniently be disposed within a commonhousing 46 which then may be bolted or otherwise afilxed to theconventional inlet assembly in chamber l8.

Although my invention has been described above with particular referenceto the use of a bimetal blade as a heat responsive means for opening andclosing the switch 48, it will be apparent that other heat responsivemeans may also be employed satisfactorily. Some of these and theirmanner of application are illustrated in Fig-' ment in the mannerexplained above. However, as the burner cools, the metal spiral willcontract, thereby closing the switch and energizing the resistanceelement. I

Alternatively the temperature responsive means may comprise a fluidactuated device which is responsive to thermal changes. The fluid may beeither gaseous or liquid. When gaseous, as illustrated in Figure 7,there may be provided a collapsible bellows 55 filled with air orothersuitable gaseous medium and suspended adjacent the bottom of thefire pot substantially in the middle of the opening I I by means of abracket 56. Stationed adjacent the bellows and supported by a bracket 51is a switch 58, which also corresponds to switch 40 of Figure 3. Switch58 is adapted to be contacted by the bellows as the latter expands underthe influence of increased temperature and to break the circuit, therebyturning off the igniter. As the burner pot cools down, however, thebellows will collapse, with the result that switch 58 will close,turning on the igniter.

In the embodiment illustrated in Figure 8, the switch controlling theigniter is actuated by means of the expansion of a liquid. Below theburner pot and adjacent thereto, as by being positioned substantially inthe center of the opening H, is a cylinder 60 which is filled with asuitable liquid. The cylinder is supported by means of the bracket 6|attached to the casing 10. An expansible bellows 62 communicates withthe cylinder through the conduit 63.. The bellows, conduit and cylinderare filled with liquid. As the temperature of the burner pot increases,the liquid will expand or become partially vaporized, resulting in theexpansion of the bellows 62 and the opening of switch 64. This breaksthe circuit and ole-energizes the electric resistance unit in the mannerexplained above. Conversely, as the burner pot cools down, the switch 64is closed, thereby reopening the circuit through the electric resistanceelement.

Electrical devices also may be employed as heat responsive elements tocontrol the operation of the igniter. 9, there may be provided adjacentthe bottom of the burner pot a thermocouple 65 connected throughelectrical conductors to the solenoid 66. The latter operates switch 61which, in turn, controls the circuit containing the igniter. As thetemperature of the burner pot rises, the current induced in thethermocouple operates the solenoid 66 which, in turn, opens switch 61,thereby de-energizing the igniter. However, as the burner pot coolsdown, the switch 61 is closed, as by means of the spring 68 and thecircuit then is re-established, thereby re-energizing the. igniter.

Light operated means also may be employed tocontrol the operation of theignition element. Such means may comprise a photoelectric cell, oralternatively a light actuated unit such as is illustrated in Figure 10.This unit 10 (Mercoid Visaflame) is contained in a tube which penetratesthe casing and burner pot ina position Thus as is illustrated in Figurepreferably slightly-above the: lower fire .ring- [4. The tube has at itsinner end a window through which; the light emanating from the burnerpasses. It then passes through a bulb contained within the tube whichactsto concentrate the light waves on a bimetal coil. The latter beingopaque changes the light energy into heat energy. and moves in responseto the developed heat. This motion is used to open a switch 12 which, inturn, opens the circuit containing the igniting element and turns itoff. However, when the flame within the burner pot is extinguished, thebimetal element moves in the opposite direction, closing the switch 12,re-establishing the circuit, and again energizing the igniting elementadjacent the burner.

To summarize the manner of operation of the oil burner igniter of myinvention, the control an first is operated to initiate the flow of oilthrough conduit I! into the burner l6, switch 48 being closed since theburner pot is cold. Contemporaneously, this closes switch 33 through theoperation of the cam 35 and cam follower 34. It also closes switch 45and opens valve 24 through lowering of the oil level in chamber 18.Closing of switches 33 and 45 makes the circuit through the resistanceelement 25 which becomes sufficiently hot to vaporize oil or othercombustible fluid picked up from the floor of the burner potand carriedto the vicinity of the resistance element through the wick 26. In thismanner, the burner is ignited initially.

The resistance element 25 remains energized until switch 33 is openedmanually, or until switch 49 is opened automatically when thetemperature within the fire pot has reached a predetermined level. Asthe temperature of the pot rises with continued operation, this affectsa tern-,- perature responsive element, placed adjacent thereto. Thiselement moves with increasing temperature or establishes an electriccircuit, the motion or the electric circuit being used to operate switch49 and to open it. This requires a substantial period of time, e. g.about seven minutes in the operation of the normal burner. During thiscritical initial period of operation, the igniter remains on so that ifsnuff. outs occur, the burner will be reignited. instantaneously. i

If, on the other hand, the snuff out should occur after the responsiveelement has operated to open switch 40 and turn off the igniter, theresult will be that the fire pot will cool rapidly because of thecooling eflect of the accumulating oil, closing switch 49 as it does so.This re-establishes the circuit through the igniting element andreignites the burner.

In the event that the snufi out should occur during a' period of powerfailure or when the circuit through the igniter has been brokenaccidentally,v the flow of oil will continue into the burnerpot untilsuch time as the flood level in the burner pot is reached 'to cause thefloat in chamber 58 to be lifted to close valve 24, thereby shutting offthe supply of oil to the chamber. At the same time as the float shutsoff the supply of oil, it also opens switch 45 through lever arm 23a.This breaks the circuit controlling the igniter, the circuit remainingbroken until the surplus oil is removed from the float chamber andburner pot. In this manner, the ignition of the accumulated oil byinadvertent re-energization of the igniter upon resumption of theelectric service is prevented.

Hence it will be apparent that, by the present invention, I haveprovided an automatic igniter for oil? burners I which will reignitevautomatically a: burner which has been snufied out, thereby preventingthe accumulation of'oil ,inthe' fire pot and attendant diiiiculty-oflightingthe-burner; Furthermore, the igniter of my invention willcontrol the operation of the burner during the critical initial ignitionperiod as well as during the continuing operation of the burner. Stillfurthenthe presently described oil burner igniter is of simpleconstruction and readily adaptable to the control ,of oil burners ofconventional con struction and free from operating hazards even in theevent of failure of the power supply.

I-Iaving now described my. invention in preferred embodiments, I claimas new and desire to. protect by Letters Patent:

1. An oil burner system comprising a burner pot, an oil burner therein,manually operated valve means connected to the burner for controllingthe flow of oil thereto, electrically operated burner ignition meansstationed adjacent, the burner, an oil supply chamber communicating withthe burner pot through said valve means, the chamber and the burner potbeing stationed relative to each other for communicating a flood levelofoil in the burner pot to the chamber when the valve means is open, anelectric circuit including the burner ignition means, electric switchmeans included in the electric circuit, and level responsive operatormeans for the switch means operable to deenergize the ignition meansupon flooding of the chamber.

-2. An oil burner system comprising a burner pot, an oil burner therein,manually operated valve means connected to the burner for controllingthe flow of oil thereto, electrically operated burner ignition meansstationed adjacent the burner, an oil supply chamber communicating withthe burner pot through said valvemeans, the chamber and the burner potbeing stationed relative to each other for communicating a flood levelof oil in the burner pot to the chamber when the valve means is open, anelectric circuit in: cluding the burner ignition means, first electric,switch means in the electric circuit, level responsive operator meansfor the first switch meansoperable to deenergize the ignition meansupon, flooding of the chamber, second electric switch, means in theelectric circuit with the ignition means, and combustion responsivemeans in heat. exchange relation with the burner pot, the combustionresponsive means being operatively associated with the second electricswitch meansand operating the same with fluctuations in burner pottemperature.

3. The oil burner system of claim 2 wherein: the combustion responsivemeans comprises a. thermostat. I

4. An oil burner system comprising a burner pot, an oil burner therein,manually operated valve means connected to the burner for controllingthe flow of oil thereto, electrically operated burner ignition meansstationed adjacent the burner, an oil supply chamber communicating withthe burner pot through said valve means, the chamber and the burner potbeing stationed relative to each other for communicating a flood levelof oil in the burner pot to the chamber when the valve means is open, anelectric circuit including the burner ignition means, first electricswitch means in the electric circuit, level responsive operator meansforthe first switch means operable to deenergize the ignition means uponflooding of the chamber, second electric switch means in the electriccircuit with the, ig-

nition means, and combustion responsive means in heat exchange relationwith the bottom of the burner pot, the combustion responsive means beingoperatively associated with the second electric switch means andoperating the same with fluctuations in burner pot temperature.

5. An oil burner system comprising a burner pot, an oil burner therein,manually operated valve means connected to the burner for controllingthe fiow of oil thereto, electrically operated burner ignition meansstationed adjacent the burner, an oil supply chamber communicating withthe burner pot through said valve means, the chamber and the burner potbeing stationed relative to each other for communicating a flood levelof oil in the burner pot to the chamber when the valve means is open, anelectric circuit including the burner ignition means, first electricswitch means in the electric circuit, level responsive operator meansfor the first switch means operable to deenergize the ignition meansupon flooding of the chamber, and included in the electric circuitsecond electric switch means operatively associated with the valve meansfor 10 operating the ignition means upon operation of the valve means.

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